Isidore later adopted the name Edgar Harburg, and came to be best known as Edgar "Yip" Harburg. He attended Townsend Harris High School, where he and Ira Gershwin, who met over a shared fondness for Gilbert and Sullivan, worked on the school paper and became lifelong friends. According to his son Ernie Harburg, Gilbert, and Irish dramatist George Bernard Shaw taught his father, a "democratic socialist, [and] sworn challenger of all tyranny against the people, that 'humor is an act of courage' and dissent".[5]

After World War I, Harburg returned to New York, and graduated from City College (later part of the City University of New York), which Ira Gershwin had initially attended with him,[6] in 1921.[7] After Harburg married and had two children, he started writing light verse for local newspapers. He became a co-owner of Consolidated Electrical Appliance Company, but the company went bankrupt following the crash of 1929, leaving Harburg "anywhere from $50,000 - $70,000 in debt,"[8] which he insisted on paying back over the course of the next few decades. At this point, Harburg and Ira Gershwin agreed that "Yip" should start writing song lyrics.

Gershwin introduced Harburg to Jay Gorney, who collaborated with him on songs for an Earl CarrollBroadway review (Earl Carroll's Sketchbook): the show was successful and Harburg was engaged as lyricist for a series of successful revues, including Americana in 1932, for which he wrote the lyrics of "Brother, Can You Spare a Dime?" to the tune of a lullaby Gorney had learned as a child in Russia. This song swept the nation, becoming an anthem of the Great Depression.

Of his work on The Wizard of Oz, his son (and biographer) Ernie Harburg has said:

“

So anyhow, Yip also wrote all the dialogue in that time and the setup to the songs and he also wrote the part where they give out the heart, the brains and the nerve, because he was the final script editor. And he — there were eleven screenwriters on that — and he pulled the whole thing together, wrote his own lines and gave the thing a coherence and unity which made it a work of art. But he doesn’t get credit for that. He gets lyrics by E. Y. Harburg, you see. But nevertheless, he put his influence on the thing.[8]

Although never a member of the Communist Party[9] (he was a member of the Socialist Party, and joked that "Yip" referred to the Young People's Socialist League, nicknamed the "Yipsels"[10]) he had been involved in radical groups, and he was blacklisted.[6] Harburg was named in a pamphlet "Red Channels: The Report of Communist Influence in Radio and Television;" his involvement with the Hollywood Democratic Committee, and his refusal to identify reputed communists, led to him being blocked from working in Hollywood films, television, and radio for twelve full years, from 1950[11] to 1962.[12] "As the writer of the lyric of the song ‘God’s Country,’ I am outraged by the suggestion that somehow I am connected with, believe in, or am sympathetic with Communist or totalitarian philosophy," he wrote to the House Un-American Activities Committee in 1950.[12] Harburg was unable to travel abroad during this period, as his passport had been revoked.[7] With a score by Sammy Fain and Harburg's lyrics, the musical Flahooley (1951) satirized the witch-hunt's hysterically anti-communist sentiment,[7] but it closed after 40 performances at the Broadhurst Theatre on Broadway. The New York critics were dismissive of the show, although it had been a success during its earlier pre-Broadway run in Philadelphia.[13]

Harburg was initially reported to have died in a traffic accident. His death was actually due to a heart attack, sustained while his car was stopped at a traffic light on Sunset Boulevard in Hollywood on March 5, 1981.[15][16]

On June 22, 2004 the American Film Institute broadcast a TV special announcing the “100 Greatest Film Songs.” “Over the Rainbow” was Number One. (“Ding Dong! The Witch Is Dead” was Number 82.)

In April 2005, the United States Postal Service issued a commemorative stamp recognizing his accomplishments.[18] The stamp is drawn from a portrait taken by photographer Barbara Bordnick in 1978 along with a rainbow and lyric from Over the Rainbow. The first day ceremony was held at the 92nd Street Y in New York.

^"E. Y. Harburg, Lyricist, Killed In Car Crash". New York Times. March 7, 1981. Retrieved 2010-11-30. E. Y. (Yip) Harburg, who wrote the lyrics for Over the Rainbow,April In Paris,Brother, Can You Spare a Dime and the musical Finian's Rainbow, died Thursday when the car he was driving swerved into oncoming traffic and collided head-on with another vehicle on Sunset Boulevard in Los Angeles. He was 84 years old. ...